As is well known in large dynamoelectric machines such as turbine generators, heat is generated therein during normal operation. To keep the machine operating within desirable temperature limits, a cooling gas such as hydrogen, is forced through the machine to carry away the generated heat. Most large turbine generators have incorporated in their design provisions for the necessary blower assemblies, heat exchangers, and passageways to ensure adequate circulation of the cooling gas which maintains the temperature of the machine during operation within the acceptable limits. In order to keep the region of the rotor winding, stator core and stator coils cool, gas must be directed through passages in these areas.
On inner cooled generators, the gas going into to rotor from both ends discharges into the air gap at the axial midpoint of the rotor and then travels to the blower at one end of the rotor where it is recirculated. Inner cooled stator coils receive gas at end which discharges into the blower at the other end. The stator core may be cooled by gas flowing axially through holes in the core or by gas flowing radially from outer diameter to inner diameter through radial vents in the core. In all cases, gas is to be prevented from bypassing these paths and flowing directly into the air gap. This is typically accomplished by an air gap barrier at one end of the generator.
Typically, the air gap baffle assembly is secured to the generator stator in the exciter end of the generator. Examples of such air gap baffle assemblies are U.S. Pat. Nos. 4,118,645; 4,315,173; and 4,654,550, each of which is assigned to the present assignee and incorporated herein by reference. Typically, these baffle assemblies comprise more than one component requiring an extended installation procedure. See, for example, FIG. 9. Additionally, some prior art designs comprise a two-piece design, wherein a first ring or member is secured to stator coils at the end region, and a removable element which bolts to the outer ring. Typically for removal of the rotor with these prior art designs, one or more pieces of the baffle assembly would need to be removed prior to insertion or removal of the rotor. Hence, installation and removal procedures for these prior art systems often involve time-consuming processes each time the rotor was inserted or removed in the generator core. Moreover, it is not uncommon for one or more segments of the air gap baffle assembly, which remain in place during rotor removal, to become damaged, thereby necessitating repair and/or replacement of those segments.